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Oral history interview of Dan Shechtman, June 17, 2015/ [persons present]: J. William (Bill) Gadzuk, Bob Shull, Mark Stiles, Jim Schooley, Frank Biancaniello, Steve Ridder, Kristen Frederick-Frost.
No full textOral history interview of Dr. Dan Shechtman conducted at the National Institute of Standards and Technology in Gaithersburg, Maryland on June 17, 2015. Dr. Shechtman, the Phillip Tobias Professor of Materials Science at the Technion in Haifa, Israel, and 2011 Nobel Laureate in chemistry for the discovery of quasicrystals, was on sabbatical from the Technion at the National Bureau of Standards, now the National Institute of Standards and Technology, in 1982 when he made his discovery
The Use of Index-Matched Beads in Optical Particle Counters
No full textIn this paper, we demonstrate the use of 2-pyridinemethanol (2P) aqueous solutions as a refractive index matching liquid. The high refractive index and low viscosity of 2P-water mixtures enables refractive index matching of beads that cannot be index matched with glycerol-water or sucrose-water solutions, such as silica beads that have the refractive index of bulk fused silica or of polymethylmethacrylate beads. Suspensions of beads in a nearly index-matching liquid are a useful tool to understand the response of particle counting instruments to particles of low optical contrast, such as aggregated protein particles. Data from flow imaging and light obscuration instruments are presented for bead diameters ranging from 6 μm to 69 μm, in a matrix liquid spanning the point of matched refractive index
Morphological and Electrical Characterization of MWCNT Papers and Pellets
No full textSix types of commercially available multiwall carbon nanotube soot were obtained and prepared into buckypapers by pellet pressing and by filtration into a paper. These samples were evaluated with respect to thickness, compressibility and electrical conductivity. DC conductivity results by two-point and four-point (van der Pauw) measurement methods as a function of preparation parameters are presented. Topology was investigated qualitatively by way of scanning electron microscopy and helium ion microscopy and from this, some generalizations about the nanotube structural properties and manufacturing technique with respect to conductivity are given
Certification of NIST Room Temperature Low-Energy and High-Energy Charpy Verification Specimens
No full textThe possibility for NIST to certify Charpy reference specimens for testing at room temperature (21 °C ± 1 °C) instead of
−40 °C was investigated by performing 130 room-temperature tests from five low-energy and four high-energy lots of steel on the three master Charpy machines located in Boulder, CO. The statistical analyses performed show that in most cases the variability of results (i.e., the experimental scatter) is reduced when testing at room temperature. For eight out of the nine lots considered, the
observed variability was lower at 21 °C than at −40 °C. The results of this study will allow NIST to satisfy requests for room-temperature Charpy verification specimens that have been received from customers for several years: testing at 21 °C removes from the verification process the operator’s skill in transferring the specimen in a timely fashion from the cooling bath to the impact position, and puts the focus back on the machine performance. For NIST, it also reduces the time and cost for certifying new verification lots. For one of the low-energy lots tested with a C-shaped hammer, we experienced two specimens jamming, which yielded unusually high values of absorbed energy. For both specimens, the signs of jamming were clearly visible. For all the low-energy lots investigated, jamming is slightly more likely to occur at 21 °C than at −40 °C, since at room temperature low-energy samples tend to remain in the test area after impact rather than exiting in the opposite direction of the pendulum swing. In the evaluation of a verification set, any jammed specimen should be removed from the analyses
SAGRAD: A Program for Neural Network Training with Simulated Annealing and the Conjugate Gradient Method
No full textSAGRAD (Simulated Annealing GRADient), a Fortran 77 program for computing neural networks for classification using batch learning, is discussed. Neural network training in SAGRAD is based on a combination of simulated annealing and Møller’s scaled conjugate gradient algorithm, the latter a variation of the traditional conjugate gradient method, better suited for the nonquadratic nature of neural networks. Different aspects of the implementation of the training process in SAGRAD are discussed, such as the efficient computation of gradients and multiplication of vectors by Hessian matrices that are required by Møller’s algorithm; the (re)initialization of weights with simulated annealing required to (re)start Møller’s algorithm the first time and each time thereafter that it shows insufficient progress in reaching a possibly local minimum; and the use of simulated annealing when Møller’s algorithm, after possibly making considerable progress, becomes stuck at a local minimum or flat area of weight space. Outlines of the scaled conjugate gradient algorithm, the simulated annealing procedure and the training process used in SAGRAD are presented together
with results from running SAGRAD on two examples of training data
(Audio) Oral history interview of John (Jack) J. Rush, September 24, 2015/ [persons present]: Bill Gadzuk, Mike Rowe, Terry Udovic, Charlie Glinka, Hank Prask, Jim Rhyne, Wen-li Wu, Dan Neumann, Kristen Frederick-Frost.
No full textOral history interview of Dr. Jack Rush, neutron-centric physical chemist/condensed matter physicist par excellence and former leader of neutron scattering research at the National Institute of Standards and Technology until 2005 where he was a NIST Senior Fellow. Since then he has remained active at the Center for Neutron Research, effectively as a Scientist Emeritus
(Audio) Oral history interview of J. William (Bill) Gadzuk, January 27, 2015/ [persons present]: Cedric Powell, Jack Russ, Joseph Stroscio, Kristen Frederick-Frost, David Lide, John Yates (by telephone)
No full textOral history interview of J. William (Bill) Gadzuk, conducted on Tuesday, January 27, 2015 at the National Institute of Standards and Technology in Gaithersburg, Maryland. Dr. Gadzuk worked at NIST and its predecessor, National Bureau of Standards, for 45 years, first doing research in surface science, surface physics and chronic molecular physics and chemical physics, mainly to do with surface phenomena
A Journey in Standard Development: The Core Manufacturing Simulation Data (CMSD) Information Model
No full textThis report documents a journey “from research to an approved standard” of a NIST-led standard development activity. That standard, Core Manufacturing Simulation Data (CMSD) information model, provides neutral structures for the efficient exchange of manufacturing data in a simulation environment. The model was standardized under the auspices of the international Simulation Interoperability Standards Organization (SISO). NIST started the research in 2001 and initiated the standardization effort in 2004. The CMSD standard was published in two SISO Products. In the first Product, the information model was defined in the Unified Modeling Language (UML) and published in 2010 as SISO-STD-008-2010. In the second Product, the information model was defined in Extensible Markup Language (XML) and published in 2013 as SISO-STD-008-01-2012. Both SISO-STD-008-2010 and SISO-STD-008-01-2012 are intended to be used together
The Optics and Alignment of the Divergent Beam Laboratory X-ray Powder Diffractometer and its Calibration Using NIST Standard Reference Materials
No full textThe laboratory X-ray powder diffractometer is one of the primary analytical tools in materials science. It is applicable to nearly any crystalline material, and with advanced data analysis methods, it can provide a wealth of information concerning sample character. Data from these machines, however, are beset by a complex aberration function that can be addressed through calibration with the use of NIST Standard Reference Materials (SRMs). Laboratory diffractometers can be set up in a range of optical geometries; considered herein are those of Bragg-Brentano divergent beam configuration using both incident and diffracted beam monochromators. We review the origin of the various aberrations affecting instruments of this geometry and the methods developed at NIST to align these machines in a first principles context. Data analysis methods are considered as being in two distinct categories: those that use empirical methods to parameterize the nature of the data for subsequent analysis, and those that use model functions to link the observation directly to a specific aspect of the experiment. We consider a multifaceted approach to instrument calibration using both the empirical and model based data analysis methods. The particular benefits of the fundamental parameters approach are reviewed